Este trabajo es apoyado por el programa Rowland junior becario. Los autores desean expresar su agradecimiento a los científicos y el personal del Instituto Rowland en Harvard: Chris Stokes por su ayuda en el desarrollo de la, la configuración de control de presión asistida por computadora hecha a la medida, Diane Schaak, Ph.D. por su aportación para la manipulación de la muestra biológica, Winfield Hill por el desarrollo de la instalación eléctrica, Alavaro Sánchez, Ph.D. para conceder el acceso a la citómetro de flujo, Scott Bevis, Kenny Spencer y Don Rogers para el mecanizado de componentes de plomería mecánicos necesarios para la configuración de presión. Maestros de microfluidos fueron fabricados en el Centro de Sistemas de nanoescala (CNS) de la Universidad de Harvard.

1. Preparación de la célula <ol><li> Placa 1 × 10 5 células / ml de metastásico línea celular de cáncer de mama MDA-MB-231 en un volumen de 10 ml por matraz de cultivo tisular T75 en de Leibovitz L-15 suplementado con 10% (v / v) de suero fetal bovino y 1 % de penicilina-estreptomicina. </li><li> Incubar MDA-MB-231 células en un incubador humidificado a 37 ° C con 0% de CO 2 medio ambiente. </li><li> Cosecha células para los experimentos de 2 días después de la siembra por tratamiento de las células con 0,25% de tripsina-EDTA durante 2 min e inactivar la actividad enzimática de tripsina mediante la adición de 8 ml de medio de crecimiento. </li><li> Precipitar las células por centrifugación durante 5 min a 200 x g y resuspender en tampón fosfato salino de Dulbecco (DPBS, 1x, sin Ca2 + y Mg2 +) a una concentración final de 5 × 10 5 células / ml. </li></ol> 2. Diseño y fabricación de dispositivos NOTA: La máscara, las fabricaciones de molde maestro y elproceso que la contiene microcanal se lleven a cabo dentro de una habitación limpia mientras que el proceso de fundición microcanal polidimetilsiloxano (PDMS) se puede realizar en una mesa de trabajo de laboratorio habitual. <ol><li> Diseñar un dispositivo de microfluidos como se ilustra en la Figura 1 con AutoCAD. El dispositivo debe consistir en una entrada con múltiples puertos de inyección, filtros gruesos y dos canales rectangulares rectas paralelas inerciales de enfoque (L = 7 mm, W = 40 m, y H = 70 m). Canal recto individual consta de 5 cámaras de electroporación, que se colocan 800 micras de separación (W C = 400 m) con dos agujeros a través de los electrodos de aluminio. Dos cámaras de electroporación transversalmente adyacentes comparten el agujero para el electrodo negativo. Dos canales rectos se funden en una salida en la región aguas abajo de la electroporación. </li><li> Convertir el archivo CAD con micro-patrones en un archivo GDSII usando LinkCAD. Escriba los micro-patrones en un 5 &quot;x 5&quot; fotomáscara en blancousando un escritor máscara de láser. Desarrollar la máscara siguiendo el protocolo del fabricante. NOTA: El proceso de desarrollo de máscara incluye desarrollo fotoprotector, grabado cromo y resistir la retirada. Alternativamente, micro-patrones impresos en una transparencia alta resolución (&gt; 20.000 dpi) se pueden comprar a partir de un fabricante de terceros y se utiliza como una fotomáscara. Características a microescala finales sobre una fotomáscara deben ser transparentes para que coincida con la polaridad de un fotoprotector negativo. </li><li> Fabricar el molde de colada del diseño del dispositivo utilizando técnicas de litografía suave estándar 23 con una capa fotorresistente negativo giró sobre una oblea de silicio de 4 pulgadas a 2.000 rpm para tener el espesor final de 70 micras. </li><li> Precocción la oblea con fotorresistencia negativa durante 20 min a 95 ° C. </li><li> Póngase en contacto con la máscara con la oblea y exponer a una fuente de UV (17,4 mJ / cm 2) durante 80 segundos utilizando un alineador de máscara. </li><li> Desarrollar la oblea expuesta durante 4 minutos en un desarrollador de SU-8. </li><li> Mida laespesor fotoprotector desarrollada usando un perfilómetro de superficie. </li><li> Mezclar con rigor una proporción de 10: 1 de elastómero de agente (kit de elastómero de silicona) curar y verter la mezcla en el molde de fundición para generar réplicas de PDMS. Desgasificar el elastómero de colada durante 30 min y curar el molde de fundición con elastómero desgasificada en un horno a 70 ° C durante 2 horas. </li><li> Delaminarse curado réplica de PDMS con patrones de microcanales de los orificios del molde y punzón para las entradas, salida y electrodos inserciones utilizando una prensa de tornillo pasador. NOTA: El diámetro normal borde de corte de la prensa de tornillo pasador debe ser 0,76 mm, adecuada para la fuerza que sostiene tubo de PEEK (OD de 1/32 &quot;) y electrodos de aluminio (OD de 0,029&quot;) en su lugar. </li><li> Crear canales de microfluidos encerrada por unión PDMS réplicas a un portaobjetos de vidrio tratado en un limpiador de oxígeno-plasma durante 7 s a una potencia y presión parcial de oxígeno de radiofrecuencia de 75 W y 500 mTorr, respectivamente. </li></ol> 3. experimentos de flujo <ol><li> Insertarelectrodos de aluminio (0,029 &quot;OD) y un tubo de PEEK de salida (1/32&quot; OD) en los lugares designados a través de agujeros en las microcanal (véase la Figura 3B). </li><li> Conectar el equipo eléctrico 18 responsable de la generación de alta tensión impulsos cortos de onda cuadrada a los electrodos de aluminio (véase la Figura 3C) que están en contacto con soluciones que fluye en el molde de PDMS. NOTA: El equipo debe constar de un generador de impulsos y un amplificador de alto voltaje construido en la casa 18. </li><li> Preparar cuatro tubos de centrífuga de 50 ml que contienen individualmente DPBS, soluciones con células y biomoléculas, y adjuntar cada tubo a su respectivo soporte del vial conectado al sistema de control de flujo neumático (véase la Figura 3A). 18 </li><li> Conectar tubo de PEEK de entrada de los titulares de los viales en los respectivos orificios de entrada en el dispositivo de microfluidos. </li><li> Establecer la magnitud de pulsos de onda cuadrada, V, 100 V, a fin de tener la fie eléctricafuerza ld, E = V / L e, a través de la cámara de electroporación ser equivalente a 0,7 kV / cm. NOTA: Aquí, L e es la distancia entre dos puntos en los que los electrodos positivos y negativos están en contacto con la solución que fluye (véase la Figura 1). </li><li> Ajuste el regulador de presión de 40 psi. NOTA:. Una fuente de nitrógeno ajustable manualmente solo se utiliza para presurizar uniformemente todos los viales de muestra y un colector de alta velocidad se utiliza para activar oportuna puertos de soluciones individuales utilizando el software LabVIEW hecha a la medida 18 </li><li> Para el control de la válvula, abra el software LabVIEW hecha a la medida marcada Válvula Runner, y haga clic en Ejecutar en el menú desplegable titulado operar. </li><li> Abra las válvulas haciendo clic en cada icono de la válvula correspondiente. NOTA: El icono de la válvula cambiará a verde cuando se activa. Al hacer clic en el icono de activo se desactivará y cerrar la válvula. El icono de la válvula cerrada debe volverse gris. </li><li> Abra la válvula del depósito DPBS (es decir., solución de lavado) para cebar la velocidad de flujo requerida para estable generación de vórtice celular-trampeo durante 1,5 min. </li><li> Cambiar el puerto solución activa de la solución de lavado a la solución de células a las células en la cámara de trampa de electroporación durante 30 segundos (es decir, el paso de células que atrapan). </li><li> Flujo ambas soluciones de lavado y de células a través del dispositivo de manera simultánea durante 10 s antes de la etapa de células que atrapan para asegurar el flujo ininterrumpido durante el paso de la solución de conmutación. NOTA: Esta breve etapa de co-flujo se debe repetir en cada paso de la solución de conmutación. </li><li> Girar en el puerto de lavado y enjuague el dispositivo durante 20 segundos con el fin de eliminar las células contaminantes no atrapados. </li><li> Se inyecta la solución que contiene la primera molécula de interés (0,2 mg / ml de 3000 Da moléculas de dextrano neutro o aniónico y 1,5 mg / ml de 70000 Da molécula de dextrano neutro) en el dispositivo. </li><li> Aplicar cinco pulsos cortos (T = 30 mseg con intervalos de 2 seg) inmediatamente después de la inyección de lasolución molecular y monitorear la magnitud y duración de los pulsos eléctricos aplicados en tiempo real, utilizando un osciloscopio. </li><li> Repita el paso 3,10 tantas veces como el número de moléculas adicionales para ser entregado. Para cada entrega molecular, incubar las células para 100 s en la solución molecular y luego enjuagar el dispositivo con la solución de lavado de 100 s para eliminar el exceso de moléculas. </li><li> Liberar las células en una placa de 96 pocillos para el análisis de aguas abajo mediante la reducción de la presión de operación por debajo de 5 psi. NOTA: Aproximadamente 100 l de solución con 100 células se obtuvieron de cada versión. </li><li> Ejecute el experimental los pasos 3.9 a través de 3.16 tres veces para recolectar suficientes células para citometría de flujo. </li><li> Centrifugar la placa de 96 pocillos que contenía células procesadas durante 5 min a 228 x g. </li><li> Eliminar el sobrenadante que contiene moléculas fluorescentes exceso. </li><li> Resuspender las células en DPBS para análisis de citometría de flujo. </li><li> Células de carga en el citómetro de flujo para u molecularptake análisis de eficiencia. </li></ol>

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Con la nueva plataforma de electroporación paralelizado, mejora de 10 veces en el rendimiento y la eficiencia de la prestación de múltiples molécula se logró, además de todas las ventajas que el sistema de una sola cámara previamente desarrollado proporciona. 18 méritos Anteriormente disponibles incluyen (i) antes de la purificación de dirigirse a las células con una distribución uniforme del tamaño para la mejora de la viabilidad, (ii) control de la dosificación precisa y molecular individual, y...

En los últimos años, el uso de pulsos eléctricos para facilitar la entrega citosólica de moléculas extracelulares se ha convertido en un medio atractivo para la manipulación de células de mamífero. 1 Este proceso, también conocido como electroporación, permeabiliza reversiblemente la membrana celular, lo que permite la membrana inherentemente moléculas impermeables para acceder al medio intracelular de las células. Debido a que prácticamente cualquier molécula se puede introducir en el citosol a través de poros creados temporales en la membrana de cualquier tipo de células por medio de electroporación, la técnica ha sido reportado como siendo más reproducible, de aplicación universal, y más eficiente que otros métodos, incluyendo mediada por virus, química y los enfoques ópticos. 2-3 Esta técnica se ha utilizado para introducir moléculas fluorescentes, 4 drogas 5 y ácidos nucleicos 6-7 manteniendo células viables e intacto. Teniendo en cuenta estos beneficios, electroporación ha sido adoptado como un trabajo comúnAtory técnica de ADN para la transfección, in vivo la terapia génica 8 y estudios de vacunación celular. Es, sin embargo, sigue siendo difícil para los sistemas convencionales de electroporación para lograr simultáneamente eficiencia práctica y la viabilidad para las muestras con gran heterogeneidad en el tamaño debido a que la intensidad de campo eléctrico requerida para la electroporación éxito se correlaciona estrechamente con el diámetro de la célula. Por otra parte, esos sistemas no permiten un control preciso de los múltiples cantidades moleculares entregado debido a la confianza en el proceso de entrega molecular estocástico mayor. 9 A fin de abordar estas cuestiones, muchos grupos han desarrollado plataformas de electroporación de microfluidos, que ofrece la ventaja de voltajes inferiores poración, mejor eficiencia de transfección, una gran reducción de la mortalidad celular, y la capacidad de ofrecer múltiples moléculas. fueron posibles 10-13 Estas ventajas debido a las pequeñas dimensiones de los sistemas de electroporación microescala cuyo electrodo de tonolongitudes son sub-milímetros, disminuyendo drásticamente tensiones requeridas para la entrega exitosa. Además, estos sistemas de electroporación microescala pueden lograr una distribución de campo eléctrico uniforme y rápidamente disipar el calor generado, produciendo mortalidad celular reducida al tiempo que mejora la eficiencia de la entrega. La utilización de materiales transparentes para estos microchips adicionales permite la observación in situ del proceso de electroporación para las modificaciones de parámetros rápidas. 2,12 Sin embargo, el control de la dosificación precisa y el control de parámetros-molecular y celular dependiente, requerido para la investigación y aplicaciones terapéuticas, 6 emergente, 14-16 todavía siguen sin resolverse. Este trabajo presenta un sistema de electroporación de microfluidos vórtice asistida, capaz de entregar múltiples moléculas secuencialmente en una población idéntica pre-seleccionado de las células diana. Las células con distribución de tamaño uniforme son aislados antes de la electroporación utilizando si se informó anteriormentemecanismo-ze selectiva de captura. 17-18 Al tener una distribución uniforme del tamaño, menor variación en la eficiencia de la electroporación y la mayor viabilidad por determinada intensidad de campo eléctrico se lograron. 19 Por otra parte, se agitaba continuamente células atrapadas utilizando vórtices microescala permitido para la entrega uniforme de moléculas a través de la citosol entero, de acuerdo con los resultados previamente reportados usando otra plataforma electroporación vórtice asistida. 20 Para demostrar que este sistema sería aplicable a una amplia gama de moléculas comúnmente utilizados en aplicaciones biológicas, macromoléculas con una amplia gama de pesos moleculares fueron entregados a metastásico de células de cáncer de mama. Además, con la ayuda de la monitorización de procesos en tiempo real, este trabajo proporciona más evidencias de poner fin al largo debate permanente sobre el mecanismo de entrega molecular durante electrporation, siendo predominantemente mediada por electroforesis versus difusión mediada. 14 </sup&gt; A diferencia de otros sistemas de electroporación, esta plataforma proporciona de forma única las ventajas combinadas de entrega precisa multi-molécula, de alta eficiencia en la entrega molecular, la mortalidad celular mínima, un amplio abanico de tamaño y cargos de moléculas entregados, así como la visualización en tiempo real de la electroporación proceso. Dadas estas capacidades, el sistema de electroporación desarrollado tiene potencial práctico como una herramienta versátil para los estudios de reprogramación celular, aplicaciones de suministro de drogas 6,14,21-22 10,19 y aplicaciones que requieren de la comprensión en profundidad de los mecanismos de entrega de electroporación moleculares.

<table><tbody><tr><td>MDA-MB-231 cancer cell line</td><td>American Type Culture Collection (ATCC)</td><td>HTB-26</td><td></td></tr><tr><td>Leibovitz&amp;rsquo;s L-15 Medium</td><td>Cellgro, Mediatech, Inc.</td><td>10-045-CV</td><td></td></tr><tr><td>Fetal bovine serum (FBS)</td><td>Gibco, Life Technologies</td><td>16000-044</td><td></td></tr><tr><td>Penicillin-streptomycin</td><td>Sigma-Aldrich</td><td>P4333</td><td></td></tr><tr><td>Dulbecco&#039;s phosphate buffered saline (DPBS)</td><td>Cellgro, Mediatech, Inc.</td><td>21-030</td><td></td></tr><tr><td>Trypsin</td><td>Gibco, Life Technologies</td><td>25200-056</td><td></td></tr><tr><td>Flow Cytometer easyCyte HT</td><td>Millipore</td><td>0500-4008</td><td></td></tr><tr><td>Oxygen Plasma Cleaner</td><td>Technics Micro-RIE</td><td></td><td></td></tr><tr><td>Dektak 6M surface profiler</td><td>Veeco</td><td></td><td></td></tr><tr><td>KMPR 1050</td><td>Microchem</td><td></td><td></td></tr><tr><td>SYLGARD 184 SILICONE ELASTOMER KIT</td><td>Dow Corning</td><td></td><td></td></tr><tr><td>Compressed Nitrogen gas</td><td>Airgas</td><td>NI 300</td><td></td></tr><tr><td>High Pressure Regulator</td><td>McMaster-Carr</td><td>6162K22</td><td></td></tr><tr><td>Downstream regulator</td><td>McMaster-Carr</td><td>4000K563</td><td></td></tr><tr><td>High-speed 3/2way-8 valve manifold</td><td>Festo</td><td></td><td></td></tr><tr><td>Inline Check Valve</td><td>Idex Health and Science</td><td>CV3320</td><td></td></tr><tr><td>5/32&quot; OD x 3/32&quot; ID Polyurethan tubes</td><td>Pneumadyne</td><td>PU-156F-0</td><td></td></tr><tr><td>1/4&quot; OD X 0.17&quot; ID Polyurethan tubes</td><td>Pneumadyne</td><td>PU-250PB-4</td><td></td></tr><tr><td>1/16&quot; PEEK tubings</td><td>Festo</td><td>P1533</td><td></td></tr><tr><td>1/32&quot; PEEK tubings</td><td>Idex Health and Science</td><td>P1569</td><td></td></tr><tr><td>PEEK tubing unions</td><td>Idex Health and Science</td><td>P881</td><td></td></tr><tr><td>Pulse Generator</td><td>HP</td><td>8110A</td><td></td></tr><tr><td>Aluminum Wire</td><td>Bob Martin Company</td><td>6061 ALUM</td><td></td></tr><tr><td>Oscilloscope</td><td>Agilent</td><td>DSO3062A</td><td></td></tr><tr><td>50 ml centrifuge tubes</td><td>VWR</td><td>21008-178</td><td></td></tr><tr><td>15 ml centrifuge tube</td><td>VWR</td><td>21008-216</td><td></td></tr><tr><td>T75 culture flask</td><td>VWR</td><td>82050-862</td><td></td></tr><tr><td>Dextran, Tetramethylrhodamine, 3,000 MW, Anionic</td><td>Gibco, Life Technologies</td><td>D3307</td><td></td></tr><tr><td>Dextran, Tetramethylrhodamine, 70,000 MW, Neutral&amp;nbsp;</td><td>Gibco, Life Technologies</td><td>D1819</td><td></td></tr><tr><td>Dextran, Texas Red, 3,000 MW, Neutral</td><td>Gibco, Life Technologies</td><td>D3329</td><td></td></tr></tbody></table>

microscale vortex-assisted electroporator for sequential molecular delivery

La electroporación ha recibido una creciente atención en los últimos años, debido a que es una técnica muy poderosa para la introducción de sondas moleculares físicamente exógenos no permeantes en las células. Este trabajo presenta una plataforma de electroporación de microfluidos capaz de realizar la entrega molécula múltiple para células de mamífero con control de parámetros precisos y molecular-dependiente. La capacidad del sistema para aislar células con una distribución de tamaño uniforme permite una menor variación en la eficiencia de la electroporación por intensidad de campo eléctrico dado; por lo tanto, una mayor viabilidad de la muestra. Además, su función de visualización de procesos permite la observación del proceso de absorción molecular fluorescente en tiempo real, lo que permite ajustes de parámetros de entrega moleculares rápidas in situ para la mejora de la eficiencia. Para mostrar las enormes capacidades de la plataforma informado, macromoléculas con diferentes tamaños y cargas eléctricas (por ejemplo, dextrano con un PM de 3.000 y 70.000 Da) fueronentregado a las células de cáncer de mama metastásico con altas eficiencias de entrega (&gt; 70%) para todas las moléculas ensayadas. La plataforma desarrollada ha demostrado su potencial de uso en la expansión de los campos de estudio en el chip técnicas de electroporación pueden ser beneficiosos.

El electroporador microfluidos paralelo desarrollado entregado macromoléculas con varios tamaños y cargas eléctricas en las células de cáncer de mama metastásico que viven. El éxito de la entrega molecular se determinó cualitativamente mediante la supervisión de los cambios en la intensidad de fluorescencia de las células que orbitan alrededor de electroporación in situ y confirmado por mediciones cuantitativas mediante análisis de citometría de flujo. Figura 4A muestra que el 90% ...

Watch this Scientific Journal Video about Microscale Vortex-assisted Electroporator for Sequential Molecular Delivery at JoVE.com

Microscale Vortex-assisted Electroporator for Sequential Molecular Delivery

Una plataforma de electroporación asistida vórtice de microfluidos fue desarrollado para la entrega secuencial de múltiples moléculas en poblaciones de células idénticas con control de la dosificación precisa e independiente. Tamaño basado electroporación anterior etapa de purificación de células diana del sistema ayudado a mejorar la eficiencia de la entrega molecular y la viabilidad celular procesada.

Vortex asistida Microscale Electroporador para entrega secuencial Molecular

Electroporation has received increasing attention in the past years, because it is a very powerful technique for physically introducing non-permeant ...

microscale-vortex-assisted-electroporator-for-sequential-molecular

Research

JoVE Journal

Bioengineering

8.5K vistas.  Harvard University.  Una plataforma de electroporación asistida vórtice de microfluidos fue desarrollado para la entrega secuencial de múltiples moléculas en poblaciones de células idénticas con control de la dosificación precisa e independiente. Tamaño basado electroporación anterior etapa de purificación de células diana del sistema ayudado a mejorar la eficiencia de la entrega molecular y la viabilidad celular procesada. 

Video: Microscale Vortex-assisted Electroporator for Sequential Molecular Delivery

Taking Advantage of Reduced Droplet-surface Interaction to Optimize Transport of Bioanalytes in Digital Microfluidics

Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of &#8220;lab-on-a-chip&#8221; platforms. Often, droplet motion relies on the wetting of a surface, directly associated with the application of an electric field; surface interactions, however, make motion dependent on droplet contents, limiting the breadth of applications of the technique.
Some alternatives have been presented to minimize this dependence. However, they rely on the addition of extra chemical species to the droplet or its surroundings, which could potentially interact with droplet moieties. Addressing this challenge, our group recently developed Field-DW devices to allow the transport of cells and proteins in DMF, without extra additives.
Here, the protocol for device fabrication and operation is provided, including the electronic interface for motion control. We also continue the studies with the devices, showing that multicellular, relatively large, model organisms can also be transported, arguably unaffected by the electric fields required for device operation.

The protocol for fabrication and operation of field dewetting devices (Field-DW) is described, as well as the preliminary studies of the effects of electric fields on droplet contents.

Tomando ventaja de la reducción de la interacción de gotas en la superficie para optimizar el transporte de Bioanalytes en microfluídica digitales

Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of &#8220;lab-on-a-chip&#8221; ...

Investigación

Ingeniería

High-Throughput DNA Plasmid Multiplexing and Transfection Using Acoustic Nanodispensing Technology

Cell transfection, indispensable for many biological studies, requires controlling many parameters for an accurate and successful achievement. Most often performed at low throughput, it is moreover time-consuming and error-prone, even more so when multiplexing several plasmids. We developed an easy, fast, and accurate method to perform cell transfection in a 384-well plate layout using acoustic droplet ejection (ADE) technology. The nanodispenser device used in this study&#160;is based on this technology and allows precise nanovolume delivery at high speed from a source well plate to a destination one. It can dispense and multiplex DNA and transfection reagent according to a predesigned spreadsheet. Here we present an optimal protocol to perform ADE-based high-throughput plasmid transfection which makes it possible to reach an efficiency of up to 90% and a nearly 100% cotransfection in cotransfection experiments. We extend initial work by proposing a user-friendly spreadsheet-based macro, able to manage up to four plasmids/wells from a library containing up to 1,536 different plasmids, and a tablet-based pipetting guide application. The macro designs the necessary template(s) of the source plate(s) and generates the ready-to-use files for the nanodispenser and tablet-based application. The four-steps transfection protocol involves i) a diluent dispense with a classical liquid handler, ii) plasmid distribution and multiplexing, iii) a transfection reagent dispense by the nanodispenser, and iv) cell plating on the prefilled wells. The described software-based control of ADE plasmid multiplexing and transfection allows even nonspecialists in the field to perform a reliable cell transfection in a fast and safe way. This method enables rapid identification of optimal settings for a given cell type and can be transposed to higher-scale and manual approaches. The protocol eases applications, such as human ORFeome protein (set of open reading frames [ORFs] in a genome) expression or CRISPR-Cas9-based gene function validation, in nonpooled screening strategies.

This protocol describes high-throughput plasmid transfection of mammalian cells in a 384-well plate using acoustic droplet ejection technology. The time-consuming, error-prone DNA dispensing and multiplexing, but also the transfection reagent dispensing, are software-driven and performed by a nanodispenser device. The cells are then seeded in these prefilled wells.

Multiplexación y transfección de plasmión de ADN de alto rendimiento mediante tecnología de nanodispensación acústica

Cell transfection, indispensable for many biological studies, requires controlling many parameters for an accurate and successful achievement. Most often ...

Genética

High Speed Droplet-based Delivery System for Passive Pumping in Microfluidic Devices

A novel microfluidic system has been developed that uses the phenomenon of passive pumping along with a user controlled droplet based fluid delivery system. Passive pumping is the phenomenon by which surface tension induced pressure differences drive fluid movement in closed channels. The automated fluid delivery system consists of a set of voltage controlled valves with micro-nozzles connected to a fluid reservoir and a control system. These voltage controlled valves offer a volumetrically precise way to deliver fluid droplets to the inlet of a microfluidic device in a high frequency manner. Based on the  dimensions demonstrated in the current study example, the system is capable of flowing 4 milliliters per minute (through a 2.2mm by 260um cross-sectional channel). Based on these same channel dimensions, fluid exchange of a point inside the channel can be achieved in as little as eight milliseconds. It is observed that there is interplay between momentum of the system (imparted by a combination of the droplets created by the valves and the fluid velocity in the channel), and the surface tension of the liquid. Where momentum provides velocity to the fluid flow (or vice-versa), equilibration of surface tension at the inlet provides a sudden stop to any flow. This sudden stop allows the user to control the flow characteristics of the channel and opens the door for a variety of biological applications, ranging anywhere from reagent delivery to drug-cell studies. It is also observed that when nozzles are aimed at the inlet at shallow angles, the droplet momentum can cause additional interesting fluid phenomena, such as mixing of multiple droplets in the inlet.

A novel microfluidic system has been developed using the phenomenon of passive pumping and a user controlled fluid delivery system. This microfluidic system has the potential to be used in a wide variety of biological applications given its low cost, ease of use, volumetric precision, high speed, repeatability and automation.

De alta velocidad basada en las gotas de entrega del sistema de bombeo pasiva en dispositivos de microfluidos

A novel microfluidic system has been developed that uses the phenomenon of passive pumping along with a user controlled droplet based fluid delivery ...

Biología

An Ultrahigh-throughput Microfluidic Platform for Single-cell Genome Sequencing

Sequencing technologies have undergone a paradigm shift from bulk to single-cell resolution in response to an evolving understanding of the role of cellular heterogeneity in biological systems. However, single-cell sequencing of large populations has been hampered by limitations in processing genomes for sequencing. In this paper, we describe a method for single-cell genome sequencing (SiC-seq) which uses droplet microfluidics to isolate, amplify, and barcode the genomes of single cells. Cell encapsulation in microgels allows the compartmentalized purification and tagmentation of DNA, while a microfluidic merger efficiently pairs each genome with a unique single-cell oligonucleotide barcode, allowing &gt;50,000 single cells to be sequenced per run. The sequencing data is demultiplexed by barcode, generating groups of reads originating from single cells. As a high-throughput and low-bias method of single-cell sequencing, SiC-seq will enable a broader range of genomic studies targeted at diverse cell populations.

Single-cell sequencing reveals genotypic heterogeneity in biological systems, but current technologies lack the throughput necessary for the deep profiling of community composition and function. Here, we describe a microfluidic workflow for sequencing &gt;50,000 single-cell genomes from diverse cell populations.

Una plataforma de ultra rendimiento microfluidos para la secuenciación del genoma de unicelular

Sequencing technologies have undergone a paradigm shift from bulk to single-cell resolution in response to an evolving understanding of the role of ...

Bioingeniería

A Droplet-Based Microfluidic Approach and Microsphere-PCR Amplification for Single-Stranded DNA Amplicons

Droplet-based microfluidics enable the reliable production of homogeneous microspheres in the microfluidic channel, providing controlled size and morphology of the obtained microsphere. A microsphere copolymerized with an acrydite-DNA probe was successfully fabricated. Different methods such as asymmetric PCR, exonuclease digestion, and isolation on streptavidin-coated magnetic beads can be used to synthesize single-stranded DNA (ssDNA). However, these methods cannot efficiently use large amounts of highly purified ssDNA. Here, we describe a microsphere-PCR protocol detailing how ssDNA can be efficiently amplified and separated from dsDNA simply by pipetting from a PCR reaction tube. The amplification of ssDNA can be applied as potential reagents for the DNA microarray and DNA-SELEX (Systematic evolution of ligands by exponential enrichment) processes.

This work provides a method for the fabrication of droplet-based microfluidic platforms and the application of polyacrylamide microspheres for microsphere-PCR amplification. The microsphere-PCR method makes it possible to obtain single-stranded DNA amplicons without separating double-stranded DNA.

Una gotita-enfoque basado en microfluidos y amplificación por PCR de microesfera para amplicones de ADN

Droplet-based microfluidics enable the reliable production of homogeneous microspheres in the microfluidic channel, providing controlled size and ...

A Multilayer Microfluidic Platform for the Conduction of Prolonged Cell-Free Gene Expression

The limitations of cell-based synthetic biology are becoming increasingly apparent as researchers aim to develop larger and more complex synthetic genetic regulatory circuits. The analysis of synthetic genetic regulatory networks in vivo is time consuming and suffers from a lack of environmental control, with exogenous synthetic components interacting with host processes resulting in undesired behavior. To overcome these issues, cell-free characterization of novel circuitry is becoming more prevalent. In vitro transcription and translation (IVTT) mixtures allow the regulation of the experimental environment and can be optimized for each unique system. The protocols presented here detail the fabrication of a multilayer microfluidic device that can be utilized to sustain IVTT reactions for prolonged durations. In contrast to batch reactions, where resources are depleted over time and (by-) products accumulate, the use of microfluidic devices allows the replenishment of resources as well as the removal of reaction products. In this manner, the cellular environment is emulated by maintaining an out-of-equilibrium environment in which the dynamic behavior of gene circuits can be investigated over extended periods of time. To fully exploit the multilayer microfluidic device, hardware and software have been integrated to automate the IVTT reactions. By combining IVTT reactions with the microfluidic platform presented here, it becomes possible to comprehensively analyze complex network behaviors, furthering our understanding of the mechanisms that regulate cellular processes.

The fabrication process of a PDMS-based, multilayer, microfluidic device that allows in vitro transcription and translation (IVTT) reactions to be performed over prolonged periods is described. Furthermore, a comprehensive overview of the hardware and software required to automate and maintain these reactions for prolonged durations is provided.

Una plataforma microfluídica multicapa para la conducción de la expresión génica sin células prolongada

The limitations of cell-based synthetic biology are becoming increasingly apparent as researchers aim to develop larger and more complex synthetic genetic ...

Electroporation of Craniofacial Mesenchyme

Electroporation is an efficient method of delivering DNA and other charged macromolecules into tissues at precise time points and in precise locations. For example, electroporation has been used with great success to study neural and retinal development in Xenopus, chicken and mouse 1-10. However, it is important to note that in all of these studies, investigators were not targeting soft tissues. Because we are interested in craniofacial development, we adapted a method to target facial mesenchyme.
When we searched the literature, we found, to our surprise, very few reports of successful gene transfer into cartilaginous tissue. The majority of these studies were gene therapy studies, such as siRNA or protein delivery into chondrogenic cell lines, or, animal models of arthritis 11-13. In other systems, such as chicken or mouse, electroporation of facial mesenchyme has been challenging (personal communications, Dept of Craniofacial Development, KCL). We hypothesized that electroporation into procartilaginous and cartilaginous tissues in Xenopus might work better. In our studies, we show that gene transfer into the facial cartilages occurs efficiently at early stages (28), when the facial primordium is still comprised of soft tissue prior to cartilage differentiation.
Xenopus is a very accessible vertebrate system for analysis of craniofacial development. Craniofacial structures are more readily visible in Xenopus than in any other vertebrate model, primarily because Xenopus embryos are fertilized externally, allowing analyses of the earliest stages, and facilitating live imaging at single cell resolution, as well as reuse of the mothers 14. Among vertebrate models developing externally, Xenopus is more useful for craniofacial analysis than zebrafish, as Xenopus larvae are larger and easier to dissect, and the developing facial region is more accessible to imaging than the equivalent region in fish. In addition, Xenopus is evolutionarily closer to humans than zebrafish (&tilde;100 million years closer) 15. Finally, at these stages, Xenopus tadpoles are transparent, and concurrent expression of fluorescent proteins or molecules will allow easy visualization of the developing cartilages. We anticipate that this approach will allow us to rapidly and efficiently test candidate molecules in an in vivo model system.

Craniofacial cartilages develop in close contact with other tissues and are difficult to manipulate in live animals. We are using electroporation to deliver molecular tools during growth of the craniofacial skeleton while bypassing early embryonic effects. This approach will allow us to efficiently test candidate molecules in vivo.

Electroporación de mesénquima craneofacial

Electroporation is an efficient method of delivering DNA and other charged macromolecules into tissues at precise time points and in precise locations. ...

Electricity-Free, Sequential Nucleic Acid and Protein Isolation

Traditional and emerging pathogens such as Enterohemorrhagic Escherichia coli (EHEC), Yersinia pestis, or prion-based diseases are of significant concern for governments, industries and medical professionals worldwide. For example, EHECs, combined with Shigella, are responsible for the deaths of approximately 325,000 children each year and are particularly prevalent in the developing world where laboratory-based identification, common in the United States, is unavailable 1. The development and distribution of low cost, field-based, point-of-care tools to aid in the rapid identification and/or diagnosis of pathogens or disease markers could dramatically alter disease progression and patient prognosis. We have developed a tool to isolate nucleic acids and proteins from a sample by solid-phase extraction (SPE) without electricity or associated laboratory equipment 2. The isolated macromolecules can be used for diagnosis either in a forward lab or using field-based point-of-care platforms. Importantly, this method provides for the direct comparison of nucleic acid and protein data from an un-split sample, offering a confidence through corroboration of genomic and proteomic analysis.
Our isolation tool utilizes the industry standard for solid-phase nucleic acid isolation, the BOOM technology, which isolates nucleic acids from a chaotropic salt solution, usually guanidine isothiocyanate, through binding to silica-based particles or filters 3. CUBRC's proprietary solid-phase extraction chemistry is used to purify protein from chaotropic salt solutions, in this case, from the waste or flow-thru following nucleic acid isolation4.
By packaging well-characterized chemistries into a small, inexpensive and simple platform, we have generated a portable system for nucleic acid and protein extraction that can be performed under a variety of conditions. The isolated nucleic acids are stable and can be transported to a position where power is available for PCR amplification while the protein content can immediately be analyzed by hand held or other immunological-based assays. The rapid identification of disease markers in the field could significantly alter the patient's outcome by directing the proper course of treatment at an earlier stage of disease progression. The tool and method described are suitable for use with virtually any infectious agent and offer the user the redundancy of multi-macromolecule type analyses while simultaneously reducing their logistical burden.

A tool and chemistries are described to sequentially isolate nucleic acids followed by proteins from a sample without the need for electricity. The tool consists of a sorbent held within a transfer pipette while the isolation chemistries are based on solid-phase extraction principles. The isolated macromolecules can be analyzed by immuno-based and PCR-based assays.

Electricidad-libre, el ácido nucleico secuencial y aislamiento de las proteínas

Traditional and emerging pathogens such as Enterohemorrhagic Escherichia coli (EHEC), Yersinia pestis, or prion-based diseases are of significant concern ...

The Fabrication and Operation of a Continuous Flow, Micro-Electroporation System with Permeabilization Detection

Current therapeutic innovations, such as CAR-T cell therapy, are heavily reliant on viral-mediated gene delivery. Although efficient, this technique is accompanied by high manufacturing costs, which has brought about an interest in using alternative methods for gene delivery. Electroporation is an electro-physical, non-viral approach for the intracellular delivery of genes and other exogenous materials. Upon the application of an electric field, the cell membrane temporarily allows molecular delivery into the cell. Typically, electroporation is performed on the macroscale to process large numbers of cells. However, this approach requires extensive empirical protocol development, which is costly when working with primary and difficult-to-transfect cell types. Lengthy protocol development, coupled with the requirement of large voltages to achieve sufficient electric-field strengths to permeabilize the cells, has led to the development of micro-scale electroporation devices. These micro-electroporation devices are manufactured using common microfabrication techniques and allow for greater experimental control with the potential to maintain high throughput capabilities. This work builds off a microfluidic-electroporation technology capable of detecting the level of cell membrane permeabilization at a single-cell level under continuous flow. However, this technology was limited to 4 cells processed per second, and thus a new approach for increasing the system throughput is proposed and presented here. This new technique, denoted as cell-population-based feedback control, considers the cell permeabilization response to a variety of electroporation pulsing conditions and determines the best-suited electroporation pulse conditions for the cell type under test. A higher-throughput mode is then used, where this 'optimal' pulse is applied to the cell suspension in transit. The steps for fabricating the device, setting up and running the microfluidic experiments, and analyzing the results are presented in detail. Finally, this micro-electroporation technology is demonstrated by delivering a DNA plasmid encoding for green fluorescent protein (GFP) into HEK293 cells.

This protocol describes the microfabrication techniques required to build a lab-on-a-chip, microfluidic electroporation device. The experimental setup performs controlled, single-cell-level transfections in a continuous flow and can be extended to higher throughputs with population-based control. An analysis is provided showcasing the ability to electrically monitor the degree of cell membrane permeabilization in real-time.

La fabricación y operación de un sistema de microelectroporación de flujo continuo con detección de permeabilización

Current therapeutic innovations, such as CAR-T cell therapy, are heavily reliant on viral-mediated gene delivery. Although efficient, this technique is ...

Dispositivo microfluídico para el aislamiento continuo de vesículas extracelulares de orina humana

Single Step Isolation of Extracellular Vesicles from Large-Volume Samples with a Bifurcated A4F Microfluidic Device

Extracellular vesicles (EVs) hold immense potential for various biomedical applications, including diagnostics, drug delivery, and regenerative medicine. Nevertheless, the current methodologies for isolating EVs present significant challenges, such as complexity, time consumption, and the need for bulky equipment, which hinders their clinical translation. To address these limitations, we aimed to develop an innovative microfluidic system based on cyclic olefin copolymer-off-stoichiometry thiol-ene (COC-OSTE) for the efficient isolation of EVs from large-volume samples in a continuous manner. By utilizing size and buoyancy-based separation, the technology used in this study achieved a significantly narrower size distribution compared to existing approaches from urine and cell media samples, enabling the targeting of specific EV size fractions in future applications. Our innovative COC-OSTE microfluidic device design, utilizing bifurcated asymmetric flow field-flow fractionation technology, offers a straightforward and continuous EV isolation approach for large-volume samples. Furthermore, the potential for mass manufacturing of this microfluidic device offers scalability and consistency, making it feasible to integrate EV isolation into routine clinical diagnostics and industrial processes, where high consistency and throughput are essential requirements.

Autor destacado: Fraccionamiento de flujo de campo asimétrico para la integración de biorreactores

Extracellular vesicles hold immense promise for biomedical applications, but current isolation methods are time-consuming and impractical for clinical use. In this study, we present a microfluidic device that enables the direct isolation of extracellular vesicles from large volumes of biofluids in a continuous manner with minimal steps.

Aislamiento en un solo paso de vesículas extracelulares a partir de muestras de gran volumen con un dispositivo microfluídico A4F bifurcado

Extracellular vesicles (EVs) hold immense potential for various biomedical applications, including diagnostics, drug delivery, and regenerative medicine. ...